1. Field of the Invention
The present invention relates to an air conditioning system, and more particularly, to an air conditioning system that can be used for both cooling and heating.
2. Discussion of the Related Art
A related art air conditioning system includes a compressor, a four-way valve, an indoor heat exchanger, and an outdoor heat exchanger that are used to perform heat exchange cycles for cooling or heating an indoor area. In heating mode, the outdoor heat exchanger is operated as an evaporator, and the indoor heat exchanger is operated as a condenser. In detail, indoor heating is performed as follows: while refrigerant is evaporated in the outdoor heat exchanger, heat is exchanged between the refrigerant and outdoor air; the refrigerant is then compressed to a high-temperature and high-pressure state by the compressor; and while the compressed refrigerant is condensed at the indoor heat exchanger, heat is exchanged between the refrigerant and indoor air.
A refrigerant heating device can be used to heat the refrigerant evaporated in the outdoor heat exchanger in heating mode. That is, in the case where refrigerant is not smoothly evaporated in the outdoor heat exchanger due to a very low outdoor temperature, the refrigerant is heated before the refrigerant is transferred to the compressor.